Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona 85287, USA; Department of Environment Research, Korea Institute of Civil Engineering and Building Technology, 283 Goyang-Daero, Ilsanseo-Gu, Goyang-Si, Gyeonggi-Do 10223, Republic of Korea.
Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, Department of Civil and Environmental Engineering, Rice University, Houston, Texas 77251, USA; College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
Water Res. 2022 Oct 1;224:119094. doi: 10.1016/j.watres.2022.119094. Epub 2022 Sep 10.
Biofouling of membrane surfaces poses significant operational challenges and costs for desalination and wastewater reuse applications. Ultraviolet (UV) light can control biofilms while reducing chemical usage and disinfection by-products, but light deliveries to membrane surfaces in spiral wound geometries has been a daunting challenge. Thin and flexible nano-enabled side-emitting optical fibers (SEOFs) are novel light delivery devices that enable disinfection or photocatalytic oxidation by radiating UV light from light-emitting diodes (LEDs). We envision SEOFs as an active membrane spacer to mitigate biofilm formation on reverse osmosis (RO) membranes. A lab-scale RO membrane apparatus equipped with SEOFs allowed comparison of UV-A (photocatalysis-enabled) versus UV-C (direct photolysis disinfection). Compared against systems without any light exposure, systems with UV-C light formed thinner-but denser-biofilms, prevented permeate flux declines due to biofouling, and maintained the highest salt rejection. Results were corroborated by in-situ optical coherence tomography and ex-situ measurements of biofilm growth on the membranes. Transcriptomic analysis showed that UV-C SEOFs down-regulated quorum sensing and surface attachment genes. In contrast, UV-A SEOFs upregulated quorum sensing, surface attachment, and oxidative stress genes, resulting in higher extracellular polymeric substances (EPS) accumulation on membrane surfaces. Overall, SEOFs that deliver a low fluence of UV-C light onto membrane surfaces are a promising non-chemical approach for mitigating biofouling formation on RO membranes.
膜表面的生物污垢给海水淡化和废水再利用等应用带来了重大的运营挑战和成本。紫外线 (UV) 光可以控制生物膜，同时减少化学物质的使用和消毒副产物，但在螺旋缠绕几何形状的膜表面输送光一直是一个艰巨的挑战。薄而灵活的纳米增强型侧向发射光纤 (SEOF) 是一种新型的光传输装置，它可以通过从发光二极管 (LED) 辐射紫外线来进行消毒或光催化氧化。我们设想 SEOF 作为一种主动膜间隔物，以减轻反渗透 (RO) 膜上生物膜的形成。配备 SEOF 的实验室规模 RO 膜装置允许比较 UV-A（光催化增强）与 UV-C（直接光解消毒）。与没有任何光照的系统相比，具有 UV-C 光的系统形成了更薄但更密集的生物膜，防止了由于生物污垢导致的渗透通量下降，并保持了最高的盐截留率。这些结果得到了膜上原位光学相干断层扫描和原位生物膜生长测量的证实。转录组分析表明，UV-C SEOF 下调了群体感应和表面附着基因。相比之下，UV-A SEOF 上调了群体感应、表面附着和氧化应激基因，导致膜表面的细胞外聚合物 (EPS) 积累增加。总的来说，将低剂量的 UV-C 光输送到膜表面的 SEOF 是一种有前途的非化学方法，可以减轻 RO 膜上生物污垢的形成。
